ProcedureMW51 (95 mg, 0.28 mmol) was stirred with methanesulfonic acid (1.82 mL, 28 mmol) at room temperature and after 1 hour (first TLC) all the starting material had been consumed. The reaction was quenched with saturated sodium carbonate and extracted with EtOAc (20 mL x2). The organic fractions were dried over magnesium sulfate, filtered and concentrated under reduced pressure.